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The Study Of Elastic And Thermodynamic Properties Of Copper、Iron、Aluminum Under High Pressure

Posted on:2015-12-19Degree:MasterType:Thesis
Country:ChinaCandidate:J J WangFull Text:PDF
GTID:2180330461485022Subject:Theoretical Physics
Abstract/Summary:PDF Full Text Request
There exists a certain internal relation between all sorts of physical properties (such as, lattice constant, linear expansion coefficient, the Debye temperature, Young’s modulus etc.) in metallic materials, however, when it is under high temperature and pressure, all of the properties are changing; thereby, affect the performance of the materials. In recent years, it’s the frontier and hot topic, which are interested the theorists, to find the association theoretically between them. Accounting for the major guidance of the experimental study and the engineering science on materials, many scholars have worked on this area.In this paper, we first introduce the investigation and current state of metallic material’s characteristic research under high-pressure; Secondly, we describe the basic method of molecular dynamics simulation and the embedded atom potential functions; finally, the study of the elastic and thermodynamic properties with copper, iron, aluminum and other metals under high pressure were given out by molecular dynamics simulation. The results of this Simulation is presented the structural changes of copper, iron and aluminum under the two stress state of tension and compression, also the elasticity and thermodynamic properties of other parameters is provided, successfully.During the simulation, weather the potential function with the metallic materials were selected properly or not,is very important and even play a decisive role in it. After analyze and validate more than once; we chose the potential functions as follows:for copper and aluminum we employ the EAM potential that fitted by mishin; however, Voter-Chen EAM potential is adopted by metallic iron. By means of these potential functions, we had calculated the elastic constants and the threshold of phase change with copper, aluminum and iron. After compared with other potential functions, we find the two potential functions which we were used to studying the elastic and thermodynamic properties of metals could reflect the elastic and thermodynamic properties of the three metallic materials accurately.The elastic properties and thermodynamic properties of single-crystal copper, iron and aluminum under high pressure have been calculated with EAM potential by means of molecular dynamics simulations. At first, we calculated the cold energy curves of several metals, then, we derive the formulas of elastic constants and other thermodynamic parameters, at the same time, the changes of physical quantities such as the Bulk modulus, shear modulus, Young’s modulus, Debye temperature, Poisson’s ratio and other parameters unde high pressure were calculated. At last, the calculation were contrasted and analyzed with the experimental values and other references results.
Keywords/Search Tags:Molecular dynamics, Elastic constant, Bulk modulus, Shear modulus, Debye temperature
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